
Tite link takes you to more on the Stylophone on Retro Thing.
Update via the comments: "I have two of the little buggers, one black and one white. The main difference, apart from the color, is that the white one is an octave higher than the black one."
Update2 via solipsistnation in the comments: "There are a few versions, actually. I had a black one, a white one, and a woodtone one, and the black was an octave lower and the woodtone had a slightly different timbre from either. It's a really simple little circuit, and it went through a bunch of iterations. Each version is slightly different.
I bought 2 of mine from this guy, and I highly recommend his refurbished Stylophones:
http://www.stylophone.co.uk/
Plus he has loads of info. Check out the 350S!"